3" might be a little too much, unless you're turbo'd. You need back pressure.

Think of it as putting ur thumb over the hole on a garden hose....
You need that sweet spot to get the most back pressure, too little and it just plops out, too much and it barely sprays.

 

I've had my share of loud / fast cars. For my everyday driver I wanted something quiet enough to not give me a headache on long trips yet not be squeamish about announcing it's power when I put my foot into it.

I took my 96 to a good muffler shop for advice. Once we were on the same page, I got the perfect set up for me. At 20 yrs old, the cat was prolly clogged and that 5 1/2' muffler wasn't giving me that low rumble that I wanted. He cut the cat out and it was empty. The honeycomb had disintegrated and was now plugging up the muffler. He offered to put straight pipe and a free flow muffler on but then we had to talk about "tone."

I get really annoyed when some punk kid moving around me in traffic with a muffler that is not only loud but sounds like a swam of pissed off bees stuck in a snare drum. I don't want to be "that guy." He suggested an insulated performance muffler to take out that "tinny" sound and give me a low tone rumble that is almost silent at idle. It is called the Thunderbolt. Made by Magnaflow and really sounds just like the welded Thrush in the video here.

Any hesitation this Blazer had from idle to stomping on the pedal is gone now. I really wasn't expecting a performance increase without adding more air/fuel goin in. Unlike the punks in their obnoxiously loud rice burners; my ride goes fast when it sounds like I it's goin fast. I do wonder if we had gone with 1/2" wider pipe all the way from the "Y" to the tailpipe if I would feel more "punch."